Regarding compounds:- it's easy to uncompound them when you know the most used words and the rules of sandhi;- you can look up the Atthakatha (this is done by a single click in CSCD http://www.tipitaka.org/cst4 ).

There's also the wonderful Digital Pali Reader (a stand-alone app for use on Firefox) though it doesn't give you the answers, it offers you suggestions, and it does make the entire Pali canon available.